JP2001264103A - Inertial navigation system, initializing method for it, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To complete initial alignment in a short time at high precision. SOLUTION: There are provided a standby alignment process (step B01) which is started upon powering-on of a system and where the output data of each sensor comprised by the system is then accumulated, a coarse alignment process (step B05) which acquires a reference coordinate from the accumulated output data of each sensor according to instruction of the initial alignment, and a fine alignment process (step B06) which calculates an error of the reference coordinate to provide a reference coordinate with higher precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inertial navigation apparatus particularly suitable for a navigation body having a long waiting time before starting navigation.
The present invention relates to an inertial navigation device initialization method and a recording medium.

[0002]

2. Description of the Related Art An inertial navigation system (hereinafter, referred to as "INS") is used to measure the position, speed, attitude, and direction of a navigating body including a flying object such as an aircraft, a ship, a vehicle, and the like during navigation.
Are widely used. Particularly, flying objects such as airplanes are used as almost indispensable devices because they have a high moving speed and a long cruising distance.

However, in the INS used in aircraft, navigation calculation coordinates are initialized in a stationary state before flight, and reference coordinates for navigation calculation are determined.

This reference coordinate is based on true north, that is, IN
True north azimuth of the reference axis of S: ψ, and the horizontal reference, ie, I
The NS reference axis pitch angle: θ and the roll angle: φ are defined by φ, and the initial value processing of the navigation calculation coordinates for obtaining ψ, θ, φ is called initial alignment.

[0005] When the initial alignment is completed, the navigation calculation can be started by actually detecting the motion of the aircraft, that is, the acceleration and the angular velocity on the determined navigation calculation coordinates.

FIG. 3 shows a flow of an initial alignment process widely used at present. Initial alignment can be broadly divided into two phases: coarse alignment and fine alignment. First, in course alignment, data from sensors such as gyros and accelerometers are accumulated and averaged to obtain a rough true north / horizontal reference. (Ψ0, θ0, φ0).

Next, in fine alignment, a true north / horizontal reference (ψ0) obtained by course alignment in the previous phase by a digital filter method such as a Kalman filter is used.
, Θ0, φ0) to estimate the error (ψ ', θ', φ ') and determine the difference to determine the accurate true north-horizontal reference (ψ, θ, φ), that is, the navigation calculation coordinates .

In order to determine highly accurate navigation calculation coordinates in a short time, it is important to optimize an estimation method such as the above-described Kalman filter in fine alignment.

The Kalman filter generally estimates the parameters to be estimated in advance and gives them as initial conditions, and performs efficient estimation calculations. As a result, the entire initial alignment process is efficiently performed, and a short time In order to stably converge the output of the Kalman filter, it is important to estimate the estimated value of the Kalman filter, that is, the estimation of the error in the course alignment.

Here, a formula of a course alignment for obtaining a generally used true north / horizontal reference (ψ0, θ0, φ0) is shown. In the following equation, Σ means accumulation of each sensor data at the time of course alignment. At the end of course alignment, a true north / horizontal reference (ψ0, θ0, φ0) is calculated using this accumulated value. That is, φ0 = tan ⁻¹ (−ΣΔVθ / ΣΔVφ) (1) θ0 = tan ⁻¹ (ΣΔVψ / (cosφ0 · ΣΔVφ−sinφ0 · ΣΔVθ)) (2) ψ0 = −tan ⁻¹ ((sinφ0 · ΣΔaφ + cosφ0)・ ΣΔaθ) / (− sinθ0 ・ cosφ0 ・ ΣΔaφ + sinθ0 ・ sinφ0 ・ ΣΔaθ + cosθ0 ・ Σaψ)) ... (3) (However, ΔV: incremental speed by accelerometer output, Δa: incremental angle by gyro output, ΔVψ, ΔVθ, ΔVφ, Δaψ) , Δaθ, Δaφ: Δ
V, Δa, yaw axis, pitch axis, and roll axis components. ) And these course alignment equations (1)
As can be seen from (3), the accuracy of the course alignment improves as data is sampled over a longer period of time.

Next, referring to FIG. 4, a description will be given of an actual operation procedure of the INS which is executed in a stationary aircraft, mainly from power-on to the above-described initial alignment.

When the power of the INS is turned on, it is repeatedly determined whether or not there is data for initializing the device and whether or not the initial alignment (ALIGN) mode is selected (steps A01 and A02). ), Wait for these inputs.

If there is data for initializing the device, it is determined in step A01 and the input process is executed (step A03). When all the data for initialization is input, It is in a state of waiting for an instruction to select the initial alignment mode in A02.

When the operator of the INS instructs the selection of the initial alignment mode at the stage of preparing for flight, this is determined in step A02.
First, the course alignment is performed as described above (step A04).

While repeatedly executing the fine alignment based on the contents obtained in the course alignment (step A05), a display indicating that the accuracy of the initial alignment has reached a certain level or more and it is possible to shift to the navigation calculation mode. It is determined whether or not "Ready Nav" has been performed (step A06), and it is determined whether or not an instruction to select the navigation calculation (NAV) mode has been made in the state where this display has been made (step A07). It waits for the navigation calculation mode selection instruction.

When an instruction to select the navigation calculation mode is issued, the mode shifts to the navigation calculation mode thereafter (step A0).
8) The navigation calculation mode is continued until it is determined that the INS has been turned off (step A09).

[0017]

As described above, in order to increase the accuracy of the initial alignment, it is necessary to first increase the accuracy of the course alignment, which is the first phase. For that purpose, sampling of data from each sensor is performed. It is useful to accumulate over a long period of time.

On the other hand, in a situation where the initial alignment mode is actually selected by the operator and the initial alignment is executed while the aircraft is stationary, the initial alignment is completed quickly, and the operation mode is promptly shifted to the navigation calculation mode and moved. And it is often desired by the operator of the aircraft to start flying.

As described above, the accuracy of the initial alignment and the required time have a trade-off relationship with the aircraft operator, and at present, depending on the model of the INS, the initial alignment requires 3 to 4 minutes. It takes some time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inertial navigation system capable of completing initial alignment in a shorter time while obtaining high accuracy. Another object of the present invention is to provide a method of initializing an inertial navigation device and a recording medium.

[0021]

According to the first aspect of the present invention,
An inertial navigation device for performing initialization including an initial alignment process prior to the start of navigation, comprising: first alignment processing means which starts upon power-on and accumulates output data of each sensor; A second alignment processing means for obtaining a first reference coordinate from the output data of each sensor accumulated by the first alignment processing means, and an error between the first reference coordinate obtained by the second alignment processing means. And third alignment processing means for obtaining a second reference coordinate with higher accuracy.

According to a second aspect of the present invention, there is provided an initialization method for performing an initial alignment process by an inertial navigation device before navigation, which is started when a power source of the device is turned on, and thereafter outputs an output of each sensor of the device. The data is accumulated, a first reference coordinate is obtained from the accumulated output data of each sensor according to the instruction of the initial alignment, an error of the first reference coordinate is calculated, and a second reference coordinate having higher accuracy is calculated. It is characterized by obtaining.

According to a third aspect of the present invention, there is provided a recording medium used in an inertial navigation device for performing an initialization including an initial alignment process prior to the start of navigation, the recording medium being started when the device is turned on, A first alignment processing step of accumulating output data of each sensor of the apparatus, and a second reference coordinate for obtaining first reference coordinates from output data of each sensor accumulated in the first alignment processing step in accordance with an instruction of initial alignment. Alignment processing step,
A control program including an instruction for causing a computer to execute an error of the first reference coordinates obtained in the second alignment processing step and a third alignment processing step of obtaining a second reference coordinate with higher accuracy. It is stored.

According to any one of the first to third aspects of the present invention, the output data of each sensor is accumulated between the time when the power of the inertial navigation system is turned on and the time when the initial alignment instruction is issued, and the initial alignment instruction is issued. Since the first reference coordinates are calculated based on the data accumulated at the time when the first reference coordinates are calculated, and the second reference coordinates with higher accuracy can be obtained by performing an error operation with respect to the first reference coordinates. If the standby time from turning on the power of the unit to giving the initial alignment instruction is long,
The initial alignment can be completed in a short time while obtaining more accurate reference coordinates.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an aircraft INS will be described below with reference to the drawings.

FIG. 1 shows a circuit configuration of the INS 10 according to the embodiment. In FIG. 1, reference numeral 11 denotes a sensor including a gyro sensor and an accelerometer (accelerometer) and a sensor unit which performs an output process of sensor data obtained by the sensors. The sensor data output from the sensor unit 11 is transmitted to a calculation processing unit 12. Sent.

The calculation processing unit 12 is composed of a small computer system such as a ROM storing a CPU and its control program, a RAM used as a work area, and the like, according to a control instruction input via the I / O unit 13. A calculation process such as initial alignment or navigation calculation using the sensor data from the sensor unit 11 is performed, and the calculation result is output to the I / O unit 13.

The I / O unit 13 is connected to the mode controller 14, the control indicator 15, and devices external to the INS 10, and performs input / output processing of various data handled by the calculation processing unit 12, control instructions, and the like. .

The mode controller 14 is installed in the vicinity of the operator of the INS 10 together with the control indicator 15, and is used to turn on / off the power, initialize the ALI (ALI).
Selection switching of a mode such as a GN) mode and a navigation calculation (NAV) mode is performed.

The control indicator 15 is a display for inputting numerical values and confirming calculation information, and a display (Read) in which a transition to the navigation calculation mode is possible in the initial alignment mode.
yNav. ) And so on.

The mode controller 14 and the control indicator 1
5 except for the sensor unit 11, the calculation processing unit 12, and the I / O
Power supply 1 for supplying operating power to O section 13 and each of these circuits
The unit 6 is unitized as an inertial navigation unit 17 and is mounted and installed at a predetermined position in the aircraft.

It is assumed that the calculation processing procedure executed by the calculation processing unit 12 is performed, for example, according to a control program installed in a recording medium (not shown) in advance.

Next, the operation of the above embodiment will be described.

FIG. 2 is a diagram for explaining an actual operational procedure mainly executed from power-on to the above-described initial alignment, which is executed on the aircraft in a stationary state by the INS 10.

When the power of the INS 10 is turned on by the mode controller 14, the calculation processing unit 12 immediately shifts to a preliminary process of a course alignment process called a standby alignment process, and samples output data from the sensor unit 11. While accumulating and storing (step B0
2) At the same time, whether or not there is data for initializing the device from the control indicator 15 (step B02) and whether or not the initial alignment (ALIGN) mode has been selected (step B03) are repeated. Wait for input.

If there is data for initializing the device, it is determined in step B02 and the input processing is executed (step B04). When all the data for initialization is input, While accumulating the output data of the sensor unit 11 by the standby alignment process in step B01, the process waits for an instruction to select the initial alignment mode in step B03.

In the standby state, the aircraft equipped with the INS 10 refuels, loads luggage,
Various operations such as inspection of various aircraft and boarding of passengers are performed at any time if the aircraft is a passenger aircraft.

Here, the sensor unit 11 is operated by these operations.
Each of the output data temporarily causes disturbance. However, by accumulating data in a longer waiting period, for example, for several tens of minutes, the output data gradually converges to a constant value and is stabilized. Become.

However, in preparation for flight, this IN
When the operator in S10 selects the initial alignment mode with the mode controller 14, it determines this in step B03 and performs course alignment using the output data of the sensor unit 11 accumulated in the standby alignment process (step B05).

In this course alignment process,
The output data of the sensor unit 11 accumulated during the standby time by the standby alignment process is used. Therefore, it is possible to calculate the true north / posture reference coordinates in a much shorter time and with higher accuracy than in the same processing shown in step A04 in FIG. 4 described above. The longer the time, the more pronounced.

Based on the reference coordinates thus obtained, while fine alignment is repeatedly executed subsequently (step B06), it is shown that the accuracy of the initial alignment has reached a certain level or more and it is possible to shift to the navigation calculation mode. It is determined whether or not the display "Ready Nav" on the control indicator 15 has become possible (step B07), and while this display is made on the control indicator 15, the navigation calculation (NAV) on the mode controller 14 by the operator is performed. ) By judging whether or not an instruction to select a mode has been made (step B08), the apparatus waits for an instruction to select an actual navigation calculation mode.

When an instruction to select the navigation calculation mode is issued, the mode shifts to the navigation calculation mode thereafter (step B0).
9) The operation of the mode controller 14 causes the INS 10
(Step B1)
0), to continue the navigation calculation mode.

In the course alignment process, since the output data of the sensor unit 11 accumulated during the standby time by the standby alignment process is used, it is assumed that true north / posture reference coordinates can be calculated with high accuracy in a short time. As described above, since the true north / posture reference coordinates can be calculated with high accuracy in this way, even when an error is calculated in the subsequent fine alignment processing, the processing time can be further reduced.

Therefore, as a result, the time from when the operator of the INS 10 selects the initial alignment mode with the mode controller 14 to when the processing in the same mode ends is compared with the conventional processing shown in FIG. Therefore, the time can be significantly reduced.

In the above embodiment, the calculation processing unit 1
2 has been described as being performed in accordance with a control program installed on a recording medium (not shown) in advance. However, the present invention is not limited to this. It may be performed in accordance with a control program input by the / O unit 13 and installed in the calculation processing unit 12.

In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0047]

According to the structure of the present invention, the output data of each sensor is accumulated between the time when the power of the inertial navigation system is turned on and the time when the initial alignment is instructed, and the time when the initial alignment is instructed. By calculating the first reference coordinates based on the data accumulated in step 1 and performing an error operation on the first reference coordinates, the second reference coordinates with higher accuracy can be obtained. In the case where the waiting time from when the initial alignment is instructed to when the initial alignment is instructed is long, it is possible to finish the initial alignment in a short time while obtaining more accurate reference coordinates.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an INS according to an embodiment of the present invention.

FIG. 2 is an exemplary flowchart showing a processing procedure in the operation of the INS according to the embodiment.

FIG. 3 is a diagram showing a flow of a general initial alignment process.

FIG. 4 is a flowchart showing a processing procedure in actual INS operation performed conventionally.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Inertial navigation device (INS) 11 ... Sensor part 12 ... Calculation processing part 13 ... I / O part 14 ... Mode controller 15 ... Control indicator 16 ... Power supply 17 ... Inertial navigation part

Claims (3)

[Claims] 1. An inertial navigation apparatus for performing initialization including initial alignment processing prior to the start of navigation, comprising: first alignment processing means which starts upon power-on and accumulates output data of each sensor; Second alignment processing means for obtaining first reference coordinates from the output data of each sensor accumulated by the first alignment processing means in accordance with an instruction for alignment; first reference coordinates obtained by the second alignment processing means And a third alignment processing means for calculating a second reference coordinate with a higher accuracy by calculating an error of the inertial navigation system. 2. An initialization method for performing an initial alignment process by an inertial navigation device before navigation, which is started upon turning on the power of the device, and thereafter accumulates output data of each sensor of the device and initializes the data. According to the alignment instruction, a first reference coordinate is obtained from the accumulated output data of the sensors, and an error of the first reference coordinate is calculated to obtain a second reference coordinate with higher accuracy. Initialization method of inertial navigation system. 3. A recording medium used in an inertial navigation system for performing initialization including an initial alignment process prior to the start of navigation, wherein the recording medium is started when a power supply of the system is turned on, and each sensor of the system is provided. A first alignment processing step of accumulating the output data of the first and second alignment processing steps; and a second alignment processing step of obtaining a first reference coordinate from the output data of each sensor accumulated in the first alignment processing step according to an instruction of initial alignment. A control program including an instruction for causing a computer to execute an error of the first reference coordinates obtained in the second alignment processing step and a third alignment processing step of obtaining a second reference coordinate with higher accuracy. A computer-readable recording medium characterized by being stored.